Tens of thousands of angry protesters staged May Day rallies in several countries of the crisis-wracked eurozone, as fury erupted at demonstrations in Bangladesh after a deadly building collapse.
Bangladeshi activists shout slogans and wave flags during a procession to mark May Day or International Workers Day in Dhaka on May 1, 2013.
Although numbers were lower than in previous years, thousands took to the streets in Spain, some brandishing flags reading "6,202,700" -- a reference to the record number of people out of work in the recession-hit state.
"This austerity is ruining and killing us," read one banner in Madrid, blasting the unpopular German-led policy of squeezing budgets in response to the eurozone's three-year debt crisis as unemployment hit 27 percent of Spain's working population.
Meanwhile, a strike in Greece stopped ferry services and disrupted public transport in Athens as workers marched against austerity in a country whose jobless rate is also around 27 percent.
Waving brightly coloured flags, nearly 13,000 people answered the call of unions and leftist groups to rally in the country, facing its sixth year of recession and making painful job cuts in efforts to appease international creditors.
Unemployment has reached a staggering 59 percent among Greece's under-25s.
In France, where unemployment has hit a record high of 3.2 million people, the far-right National Front party of Marine Le Pen, which also traditionally marches on May 1, called for a light of hope in a France "locked in the darkness of Europe".
France "is sinking into an absurd policy of endless austerity ... because it's about always saying yes to Brussels, to Berlin of course, and to financial moguls in all circumstances," she said.
Pope Francis meanwhile used a private mass in his residence to mark May Day, urging political leaders to fight unemployment in a sweeping critique of "selfish profit" that he said "goes against God".
He slammed as "slave labour" conditions in the Bangladesh factory that collapsed last week killing more than 400 workers, with employees paid just 38 euros ($50) a month.
In Dhaka, protesters holding red banners and flags chanted "Hang the Killers, Hang the Factory Owners" after the devastating caving in of the garment factory, as rescuers warned the final toll could surpass 500.
Police put the number of protesters at the main rally at more than 20,000, with smaller-scale protests elsewhere in the Bangladeshi capital and other cities.
In Turkey's biggest city Istanbul, police fired tear gas and water cannon at stone-throwing protesters trying to gather for a banned demonstration.
More than 30 people, mostly police, were injured and 72 arrests were made as fighting erupted in three neighbourhoods leading to Taksim Square -- a traditional hub for leftist May Day protests -- where authorities had blocked off the streets.
And some 20,000 protested in Croatia, where unemployment stands at 22 percent and union leaders warned they were giving their government a "last chance to change direction".
Thousands marched in Portugal, with anger directed against the so-called Troika -- the European Commission, European Central Bank and International Monetary Fund -- that has imposed strict austerity measures in return for bailouts worth billions of euros.
In Berlin, traditional scene of May Day clashes, far-left militants smashed bank windows, vandalised cars and threw stones at police, officers said.
Earlier, members of the neo-Nazi NPD faced off with counter-demonstrators. Police said stones and bottles had been thrown, and some 20 arrests were made.
About 40,000 residents of the southern district of Kreuzberg, usually plagued by violent incidents, turned out to demonstrate for peace.
Even in relatively wealthy Switzerland, not part of the European Union, nearly 13,000 people demonstrated against the income gap between bosses and employees.
Some 2,000 demonstrators marched in Los Angeles calling for immigration reform, a key issue just north of the US-Mexican border.
Two marches wound their way through the California city's downtown district, with community and faith groups joining labor unions supporting legislation to end deportations.
"The ability of immigrants to come out of the shadows and find better jobs is something that's never been more important," said Jacob Hay of the SEIU United Service Workers West.
Meanwhile, in Russia, President Vladimir Putin revived the Soviet-era May Day tradition of handing out "Hero of Labour" awards.
"Creating a strong, wealthy Russia is possible only with hard work," Putin said as he awarded medals to five people, including prominent conductor Valery Gergiev and a Siberian coalminer.
Police in Sunni Muslim-ruled Bahrain fired tear gas to disperse May Day demonstrators demanding the reinstatement of Shiites sacked from their jobs during pro-democracy protests two years ago, witnesses said.
Thousands took to the streets of Rabat and Casablanca demanding jobs and higher pay, with a large security contingent deployed in the Moroccan capital.
In the West African state of Senegal, unions used a large May Day assembly to announce an end to the "grace period" enjoyed by President Macky Sall, elected over a year ago.
Electricity blackouts are a regular occurrence and the unions are demanding lower prices for basic necessities such as rice, sugar and cooking oil in the country of 13 million where most live in poverty.
In Bolivia, President Evo Morales announced the expulsion of USAID, accusing the US development agency of meddling in the country's internal affairs in a new souring of often tense relations.